Chemical ecology of lichens and species composition of cryptogams among three boreal habitats in eastern Manitoba

Abstract

The Precambrian Shield supports a diversity of cryptogams where environmental conditions predict their distribution. Moisture and light are thought to affect secondary metabolite production in lichens, leading to a hypothesis of chemical communities that may be independent of species assemblages. Hypotheses were that habitats will be characterized by lichen secondary metabolites and that lichen and bryophyte species composition will also distinguish among habitats. Lichens and bryophytes were sampled from six quadrats from each of two sites within each of three habitats (rock faces, rock outcrops, and forest floors). This study showed strong relationships among species assemblages, secondary metabolites, and types of habitat. Species abundance, cover, and species richness also differed among habitats. Individual secondary metabolites could differentiate among three habitats, suggesting that certain metabolites such as usnic and squamatic acids would more likely be found in habitats such as dry exposed rock outcrops than in moist shaded habitats. Individual analyses suggested that some secondary metabolites may serve multiple functions in a habitat, such as triterpenes, while others may have more specific functions, such as salazinic acid, where environmental features may be important for secondary metabolite production. Further investigation of specific metabolites is needed to understand their roles in adaptation.